微波结合常规烧结Y-TZP、ZTA陶瓷的介电性能随温度变化的实测与模拟研究

This project is proposed to carry out the actual measurement and analog simulation study on the variation of dielectric property with temperature for Y-TZP and ZTA ceramics sintered with microwave-conventional combination method. The initial simulation results about the electromagnetic field distribution of ceramics placed in the microwave cavity as well as the boundary conditions will be used in temperature field simulation software 'Ephysics' ,with which to simulate the change of ε,tgδwith temperature of the sample when using microwave sintering. The actual measurement technique named microwave reflection ratio will be used to measure the change of dielectric values with temperature of samples. Actual measured value and simulated value will be compared to analyze the difference and effect factors, meanwhile, the 'Critical temperature' for sharp increases in dielectric property will be found out during the sintering process of Y-TZP and ZTA ceramics. The microwave-conventional sintering of sample will be conducted, during the sintering process, infrared temperature measurement and thermal imaging technology will be used to monitor the variation of temperature, shape and the dimension, the sintering mode will be changed at critical temperature. Electronic microscope and XRD will be used to analyze the microstructure of sintered sample, the effects of sintering temperature and geometric dimensions of the sample to the dielectric property will be discussed, the functional relations of ε,tgδwith the temperature will be revealed, and related database will be constructed to provide technical support for the microwave-conventional combination sintering

本项目提出开展微波结合常规烧结Y-TZP、ZTA陶瓷的介电性能随温度变化规律研究，将前期采用三维电磁仿真技术对Y-TZP、ZTA陶瓷在微波烧结腔内电磁场分布研究的结果以及相应的边界条件应用于温度场仿真软件Ephysics，以此来模拟研究试样的ε、tgδ在微波烧结过程中随温度场的变化状况。采用微波反射比实测技术测定试样的介电性能随烧结温度的变化值，将实测数据与模拟数据进行对比，分析其差异及影响因素，找到Y-TZP、ZTA试样在烧结过程中存在介电损耗急剧增加的临界温度。将试样在微波结合常规烧结设备中进行实际烧结，用红外测温和热成像技术监测试样的温度和尺寸变化，在临界温度时进行烧结方式的转换。用电镜和X射线衍射等仪器对烧成试样进行分析，探讨试样的不同烧结温度和几何尺寸等因素对介电性能的影响，得出ε、tgδ随温度变化的函数关系，建立与此相关的数据库，为有效实施微波结合常规烧结技术提供理论支撑。

结构陶瓷材料具有高强度、高硬度、耐腐蚀、耐高温等特征，成为新材料的重要发展领域，受到广泛关注，其主要制备工艺为：粉料制备、成型和烧结。其中，烧结工艺技术对材料的性能和产品成本起到至关重要的作用。.本项目采用三维仿真软件Ephysics对Y-TZP和ZTA试样在微波结合常规烧结过程中温度场的分布进行模拟仿真分析，描述出在材料介电性能变化条件下试样内的温度场分布情况，找到了烧结陶瓷材料时烧结腔内的试样上的温度随介电性能突变的数据。分析烧结腔内试样的介电性能随温度的变化规律，测定了Y-TZP、ZTA材料的介电性能随烧结温度的变化状况，将实际测试的数据与模拟计算的数据进行对比，分析其影响因素，获得结构陶瓷材料介电性能随温度变化的规律，掌握陶瓷材料的临界温度数据，用电镜对烧成试样进行分析，研究了试样的不同烧结温度对介电性能的影响。.研究表明：将3Y-TZP、ZTA陶瓷素坯预加热到临界温度点再进行微波烧结，避免了坯体在低温阶段形成局部热斑，当温度升高到临界温度点使整个坯体都对微波具有很强耦合能力时，微波能基本上被坯体吸收。从而解决陶瓷材料在低温时对微波能吸收能力很差，出现非均匀性加热等问题。采用“先常规在临界温度后再微波”的烧结工艺不仅大大的缩短了烧结时间，降低了烧结温度，提高了生产效率，同时对陶瓷的性能也有显著提高,并成功制备出纳米陶瓷。